Unsaturated lipids such as polyunsaturated fatty acids and their esterified derivatives (phospholipids and triacylglycerols), sphingolipids, and cholesterol will he oxidized using a variety of relatively mild conditions and the products mixtures and individual products isolated from the mixtures will he tested for mutagenicity against test strains of Salmonella typhimurium (the Ames test). The mutagenicity testing will depend on perfection of a preincubation procedure to ensure adequacy of the test protocol and to allow assay in the presence of test sample toxicity. Any mutagenic preparations will be fractionated by thin-layer and high performance liquid chromatography and fractions and individual pure derivatives will also be tested. Mutagenicity of oxidized lipids will be examined to determine whether derivatives are mutagenic per se or whether they give rise to active oxygen species that are the mutagenic components of the mixtures. These studies should be of importance in trying to determine whether processed lipid-rich foods that are subject to oxidation and deterioration on processing or storage pose problems of mutagenicity.